4 Insect Life : Its Why and Wherefore 
of the mixed company that exists in a 
houseful of flies, but as the house fly 
predominates largely in numbers, and as 
our article has to do with this one species 
of fly, we will proceed to discuss his 
peculiarities. 
His Haunts. — The “ Musca domestica ” 
commonly lays its eggs on horse manure, 
as this substance seems to be the favourite 
food of the larva ; it will also oviposit on 
cow dung or in excrement of every kind, 
and if such be not available, it will breed 
in decaying animal or vegetable substances 
of any nature — even in slops and fermenting 
liquid matter. The eggs are minute, 
elongated ovals of a dull chalky white, each 
female laying an average of 120 at a time. 
These eggs hatch in about eight hours. 
The larval period, i.e., the time when it 
assumes the form of a tiny maggot, lasts 
five days, after which time the pupal or 
chrysalis form is reached, which after 
another five days produces the perfected fly. 
The development of a generation thus 
takes about ten days. This period is to 
a certain degree dependent upon the 
surrounding temperature, etc. Recent 
